BRASILIA/SAO PAULO (Reuters) - Brazil's federal police on Friday raided the headquarters of Latin America's largest independent investment bank, Banco BTG Pactual SA
Maria das Gracas Foster, former chief executive of state-controlled oil company Petroleo Brasileiro SA
BTG Pactual confirmed in a securities filing its headquarters in Sao Paulo and Rio de Janeiro were raided by federal police and said it was operating normally.
Shares of BTG Pactual were down almost 14% in mid-afternoon trading in Sao Paulo, at 57.90 reais.
The bank said it was cooperating with authorities and the raids were related to a plea deal signed by former minister, Antonio Palocci.
It said an investigation by a special independent committee led by lawfirm Quinn Emanuel Urqhart & Sullivan LLP had already been carried out and no evidence of unlawful conduct was found.
One source close to the bank said previous federal police probes had gotten the same documents they were searching on Friday.
Prosecutors are investigating whether Petrobras, as the state-run company is known, sold stakes in Nigerian oilfields to BTG in 2013 for a value lower than initial assessments by other financial institutions.
"In the beginning of the sale process, the assets were valued between $5.6 billion and $8.4 billion. But in the end, BTG Pactual paid $1.5 billion for a 50% stake," the statement from prosecutors said. It also mentioned potential bribes related to the acquisition of oil rigs.
Petrobras sold its 50% stake in Petrobras Oil and Gas BV, known as Petroafrica, to Vitol SA last year. BTG kept its stake.
BTG Pactual founder Andre Esteves last month asked the central bank to allow him to take back a key stake in the bank's controlling partnership after he was acquitted on different corruption charges.
(Reporting by Lisandra Paraguassu and Ricardo Britto in Brasilia and Paula Laier in Sao Paulo; Editing by Bernadette Baum and Tom Brown)